Water heater control system



April 2, 1935.

V. G. VAUGHAN WATER HEATER CONTROL SYSTEM Filed Oct. 29, 19-30 A ut .5

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UNITED STATES PATENT OFFICE WATER HEATER CONTROL SYSTEM Victor G. Vaughan, Mansfield, Ohio, assignor to Westinghouse Electric & Manufacturing Company, a corporation of Pennsylvania Application October 29, 1930, Serial No. 491,939

19 Claims. (01. 219-39) My invention relates to water heaters and parof the kind shown in Patent No. 1,697,886 to J. A. ticularly to control systems for tank heaters. Spencer, and includes a base it, a plurality of An object of my invention is to provide a conarcuate contact members 2| thereon, a naptrol system for a water heater that will limit the acting bimetal disc 22 having contact bridging 5 maximum energy input into a tank of water to members 23 mounted thereon which either en- 5 be heated. gage, or are disengaged from the stationary con- Another object of my invention is to provide a tact members 2 I. For further details of this concontrol system for a water heater that will ef- S uetlon, refe ence maybe had to the above menfect selective energization of a plurality of electiened Spencer P tric heating units under predetermined conditions A l w r h at n unit 6 has an ther thermo- 10 of demand for hot water. static switch assembly 21 operatively associated In practicing my invention, I provide, in comtherewith which is of substantially the same genbination with a water tank that is preferably eral construction as element i8 but differs thereheat insulated, a lower and an upper electric from in beineprovided W h a relatively mall heating unit, the upper unit being provided ith heating element 28, connected in the manner 1 a thermostatic control switch closely associated wn more pa t u a y in 2, t c nn ct it therewith, The lower heating t i provided in circuit or to disconnect it from the circuit to with a thermostatic switch and means operativepermit of Varying the p at e o t e Wate 1y so i ted ith th some t permit of varying at which the thermostatic switch will operate.

the temperature at which it will operate. I pro- Reference y n w be h to Fi 2 f the draw- 20 vide also an electromagnetically controlled switch 8 1 8 diagram of connections f h ntire for controlling the circuit of the lower heater in o t system which may i ud suppl -c rcuit accordance with the current traversing the upper Conductors 1 and 2- An electromagnetic relay h t 3i includes a fluid switch 32, pivotally mounted 5 In t single h t of d i on a suspension member 33, shown generally only,

Figure 1 1 a View, in vertical t through an actuating coil 34 and a movable core member a tank installation with which is associated the 36 energized by th coil 34 d vi stir up system embodying my invention, connection 31 to one end of the pivotally mounted Fig. 2 is a schematic diagram of connections w h 32 to permit of V y h P sition of the of the system embodying my invention, nd latter. The actuating coil 34 is connected in Figs, 3, 4 a d 5 are vi w f a, manually perseries-circuit with the thermostatic switch l9 and able control switch illustrating positions thereof h resistor 01 heating unit 1, nd allot these which differ from that shown in Fig. 2 of the elements are connected to supply-circuit'conducdrawing. tors Li and 1a.

35 Referring first to Fig. 1 of the drawing, I have -The small auxiliary heater 28, associated with there illustrated a tank ll having a cold-water thermostatic switch 21, is controlled by a p inlet pipe I2 and a hot-water outlet pipe It asswitch 38 which is shown in fully assembled sociated therewith. An external casing l4, which posi i n in Fi 1 f he rawing but is shown may be made of relatively thin sheet metal, surin exploded position in Figs. 2 to 5, inclusive, of

40 rounds the tank II and is spaced therefrom to the drawing. The switch 38 comprises a single permit of locating therebetween a mass it of a shaft 39, having a plurality of bridging members suitable heat-insulating material. 4|, 42, 43 and 44 located thereon, in coaxial An upper electric heating element I! has a spaced relation, to cooperate with a plurality of thermostatic switch assembly I9 closely associfixed contact members, which are indicated by 45 ated therewith, the structure being preferably the relatively small circles within the larger 45 that disclosed and claimed in my Patent No. circles shown as surrounding the contact-bridg- 1,715,687 issued June 4, 1929. It is to be undering members 4| to 44, inclusive. Switches of this stood that the thermostatic switch I8 is eflec-i.v general kind are already well known in the art, tive to control the circuit of the heating element and I have, therefore, shown a switch schemat- H, which is shown as including a resistor (not ically only, as it.constitutes,-speciflca1ly, no part 50 shown in detail in Fig. 1 of the drawing, but of my present invention.

shown schematically in Fig. 2 of the drawing) A second small resistor 48 is provided which is as being located within a suitable tubular metal connected in circuit with the control system, in casing. a manner to be hereinafter set forth.

The thermostatic switch assembly ll may be Let it be assumed that the tank II is fllled with 55 hot water and that, initially, the temperature of the water is sumciently high to insure that switches l8 and 21 will have been actuated to their open positions. As is usual, the hotter water will be located at the top 01 the tank and this will, therefore, insure that the switch is will have been moved to its open position before switch 21 was moved to its open position. when switch [8 is open, coil 34 of relay 3! is deenergized, and current can flow through the resistor 01 heating unit 26, provided that switch 21 is. in its closed position.

Let it be assumed that a relatively small quantity of water is drawn from the tank. This hot water will be drawn from the top of the tank rather than from the bottom, so that the thermostatic switch l8 will be maintained in its open position and, as soon as the temperature of the surrounding water and of switch 21 has dropped to the required value at which the latter will close, the heater 26 will be energized to heat the water in the bottom of the tank. In other words, the

bottom heater will be efiective during the times of ordinary demand for hot water from the tank to heat the water in accordance with the amount of energy expended in the resistor 01- heating unit 26, and, in accordance with the setting of switch 38, the efiect of which isnow to be described in detail.

Switch 38 is provided with five terminals, and connections are made from these terminals as is shown more particularly in Fig. 2 of the drawing. Terminal '5! is connected to one terminal or the fluid switch 32. Terminal %';2 is connected to an auxiliary terminal of switch 2?. Terminal 53 -is connected to a main terminal of switch 2?.

Terminal es is connected to one terminal of heating unit 2%, while terminal as is connected to supply-circuit conductor Li. A: sixth terminal Ei'i may be provided to be connected to one end oi? resistor 56, the other end of which is connected to terminal 52. Tracing the circuit of Fig. 2, which shows the condition when thermostatic switch is is in its open position, and thermostatic switch 2? is in its closed position, it will be noted that resistor dB and auxiliary heating element 2% are short circuited.

Referring now to Fig. 3 of the drawing, switch 38 has been turned through one quarter turn and it will be noted that heating unit 28 of switch 2i and resistor as are connected in parallel-circuit relation to each other and in series with resistor of heating unit 26. The heating unit it is, therefore, energized to a predetermined degree and tends to raise the temperature of the bimetal disc to cause it to snap into its open position at a lower temperature of the surrounding water than was the case when connected as shown in Fig. 2.

Referring to Fig. 4 of the drawing, a similar tracing of the circuit of resistor Q6 and heating unit 28 will show that heating unit 28 is alone connected in series circuit with the resistor of heating unit 2d, and that resistor 46 is disconnected from the circuit. It is understood, of course, that switch 38 has been moved through another quarter turn. A larger value of current will, therefore, traverse heating unit 23 to cause it to have a greater efiect upon the bimetal disc of switch 21, so that a lower temperature of the surrounding body of water will be suflicient to cause the switch to be moved to its open position.

Fig. 0! the drawing shows the relatitve positions of the movable contact-bridging members when the switch has been given a third one .demand for hot water.

quarter turn, in which case all oi the circuits are open.

In case it happens that substantially all or the water in the tank has been withdrawn therefrom, as by an excessive, demand, it will be apparent that the thermostatic switch l8, associated with the r per heater, will be moved to its closed position, whereby the resistor of heating unit l1 and the actuating coil 34 are both energized. The heating unit II will, therefore, heat a small quantity of water at the too of the tank in order to be ready to meet, to some degree, at least, a The energized coil 36 will cause a tilting movement of switch 22, whereby the circuit through heating unit 26 and switch '28, which will now become effective to heat the water remaining in the tank to the desired degree.

The device or system embodying my invention thus provides a relatively simple means for insuring that a reasonable supply .of hot water shall be available at all times, and that at least a lesser quantity oi hot water shall be made available within a short time after a sudden maximum demand has occurred. The system further provides means for limiting the maximum energy input which y be drawn from an energy-supply circuit.

Various modifications of my invention may be made without departing from the spirit and scope thereof, and I desire, therefore, that only such limitations shall be placed thereon as are imposed by the prior art, or are set forth in the appended claims.

I claim as my invention:

1. A water heater having a tank and electric heating units at the top and at the bottom portions thereof, a thermally-actuable switch controlling the circuit of the top heater and efiective to interrupt the top heater circuit when the temperature of the water at the top of the tank is above a predeteed value, and an electromagnetic switch in the circuit of the bottom heater and controlled by the current traversing the top heater for interrupting the energization of the bottom heater upon energization of the top heater by reason of the water temperature in the top of the tank falling below a predetermined value.

2. A water heater including a tank, electric heating units for said tank at the top and at the bottom portions thereof, and thermally-actuated switches for controlling the respective heating units, a switch for controlling the circuit of the bottom heater and means controlled by the current traversing the top thermally-actuated switch for actuating the circuit-controlling switch of the bottom heater to its open position when the top heater is energized.

3. A water heater including a tank, heating units for the top and the bottom of the tank, thermally-actuable means operatively associated with the respective heaters for efiecting deenergization of the lower heater and energization of the upper heater upon filling the tank with cold water and for eiiecting deenergization of the upper heater and energization of the lower heater upon heating of a predetermined quantity of water in the top of the tank to a predetermined temperature.

4. A water heater including a tank, heating units for the top and the bottom of the tank,

- thermally-actuable means operatively associated with the respective heaters for eflecting deenergization of the lower heater and energization of the upper heater upon filling the tank with cold water and for etl'ecting deenergization of the upper heater and energization of the lower heater upon heating 01' a predetermined quantity of water in the top or the tank to a predetermined temperature, and for deenergizing the lower heater upon heating of all of the water in the tank to a predetermined temperature.

5. A device as set forth in claim 4 in which the thermally-actuable means for the lower heater is provided with means for varying the temperature at which it will deenergize the associated heater.

6. A device as set forth in claim 4, in which the thermally-actuable means for the lower heater is provided with manually adJustable means for varying the temperature at which it will deenergize the associated heater.

7. A liquid heater comprising a tank, means for applying heat to diiterent portions of said tank, means dependent upon the temperature of the liquid in one of said portions for controlling said heating means so that said heating means applies heat to said different portions selectively, and means dependent upon the temperatures 0! the liquid in said portions respectively for controlling said heating meansso as to render the heating means for each portion inefl'ective when the liquid in that portion has attained a'predetermined high temperature.

8. A liquid heater comprising a tank, heating means for the upper portion of said tank, heating means for the lower portion 01' said tank, and means responsive to the temperature 01 the liquid in the upper portion or said tank for controlling both of said heating means so that when the liquid in said upper portion has attained a predetermined high temperature the heating means for said portion is rendered ineffective and the heating means for said lower portion is rendered eflective.

9. An electric liquid heater comprising a tank, electrical heating means for heating the liquid in the upper portion of said tank, electrical heating means for heating the liquid in the lower portion of said tank, means responsive to the temperatures of the liquid in the upper portion 01' said tank for controlling both of said heating means so that when the liquid in said upper portion has attained a predetermined high temperature the heating means for said upper portion is disconnected and the heating means for said lower portion is rendered effective, and means responsive to the temperature or the liquid in the lower portion of said tank for controlling the lower heating means so that said heating means is disconnected when the liquid in said lower portion attains a predetermined high temperature.

10. An electric water heater comprising a tank, an electrical heating element for the upper portion of said tank, a second electrical heating element for the lower portion of said tank, means responsive to the temperature of the water in the upper portion or said tank for}. controlling both of said heating elements and responsive to the temperature or the water in the lower portion or said tank for controlling 'said second heating element.

11. An electric water heater comprising a tank, an electrical heating element for the upper portion of said tank, a second electrl heating element for the lower portion or said tank, means responsive to the temperature of the water in the upper portion of said tank for controlling both of said heating elements so that said upper .element is deenergized and said lower element is energized'when the temperature or the water in said upper portion has attained a predetermined high value, and a temperature cut out for said lower element responsive to the temperature 01' the water in the lower portion of said tank.

12. A water heater comprising a storage tank, a hot water draw ed at the upper portion of said tank, a cold water inlet at the lower portion of said tank, means for applying heat to the upper and lower portions or said tank, means responsive to the temperatures or the water in said upper and lower portions for controlling said heating means so that in the event the cold water line reaches a predetermined level heat is applied only to the lower portion or said tank and in the event the cold water line reaches a higher predetermined level heat is applied only to the upper portion of said tank.

13. An electric water heater comprising a tank, an electrical heating element for the upper portion of said tank, an electrical heating element for the lower portion of said tank, means responsive to the temperature of the liquid in said upper portion for controlling both of said heating elements so that said upper element is deenergized and said lower element is energized when the water in said upper portion attains a predetermined high temperature, and upon the water in said portion attaining a predetermined low temperature said upper element is energized and the lower element is deenergized, and a temperature cut out responsive to the temperature 0! the water in the lower portion of said tank for shutting off said lower heating element when the temperature 01' the water in said lower portion attains a predetermined high value. I

14. An electric water heater comprising a tank, an electrical heating element for the upper portion oi said tank, an electrical heating element for the lower portion of said tank, thermostatic means responsive to the temperatures or the water in said upper and lower portions for controlling said heating elements so that when the temperature of the water in the upper portion of said tank reaches a predetermined low value said upper unit is energized so as to heat the water in the upper portion of said tank to a predetermined high value whereupon said element is deenersized and said lower element is energized to heat the water in the lower portion of said tank to substantially said predetermined high value whereupon said lower element is deenergized, and upon the water in the lower portion or said tank attaining a predetermined low temperature said lower element is reenergized.

15. A water heater comprising a storage tank, a hot water draw of! at the upper portion of said tank, a cold water inlet at the lower portion or said tank, means for applying heat to the upper and lower portions of said tank, means responsive to the temperature of the water in said upper and lower portions for controlling said heating means so that while the hot water consumption does not exceed apredetermined rate, heat is applied only to the lower portion of said tank so as to maintain the hot water supply, but in the event the hot water consumption exceeds said predetermined rate, heat is applied only to the upper portion 01' said tank so as to heat that portion of the water which is available for immediate use.

16. An electric water heater as set forth in claim 10 in which the means responsive to the sponsive to the temperature oi the water in the lower portion of the tank is provided with manually adjustable means whereby it will be caused to shut ofl the lower heating element at a temperature of the water in the lower portion of the tank which is lower than said predetermined high value.

18. An electric water heater as set forth in claim 13 in which the temperature cut-out responsive to the temperature of the water in the lower portion of the tank is provided with an auxiliary current-traversed heating element 10- mecca cated in heat transferring relation therewith and manually-actuable control means therefor to vary the temperature orthe water in the lower portion of the tank at which it will shut oil. the lower heating element.

19. An electric water heater, as set forth in claim 13 in which the temperature cut-out responsive to the temperature of the water in the lower portion of the tank is provided with an auxiliary electric heating element located in heat transferring relation therewith, a second auxiliary electric resistor out of thermal relation therewith, a manually actuable plural-contact plural-position switch and electric connections between the two auxiliary electric heating and resistor elements, the cut-out and the switch to. vary the temperature of the water in the lower portion of the tank at which the cut-out will operate.

VICTOR G. VAUGHAN. 20 

